It messes your hair and you have to wear uncool clothes.
Flippant as they sound, these are among the main reasons behind a sharp decline in teenage girls' participation in sport. The gender gap is especially evident in secondaries, where self-image becomes more important for pupils.
But now, alternatives to traditional PE are helping to stop the rot. Street dances, such as hip-hop and break-dancing, and mountain biking are appealing to youngsters.
The Scottish Health Survey reported in 1998 that 27 per cent of boys and 40 per cent of girls are not active enough to meet the minimum guidelines (an accumulation of one hour a day on most days of the week). By 16, two in three girls and one in three boys do not meet the recommended minimum level.
Those from higher income households that can boast educational qualifications are more likely to exercise than those from deprived areas with lower educational attainment.
"Feedback suggests that a core group regularly do not participate in secondary PE," says Mary Allison, the Scottish physical activity co-ordinator. "But what is being offered is not engaging, otherwise more pupils would want to do it. Boys and girls in Scotland are not any less active than their average counterparts across Europe. It is a global trend driven by such things as television, car usage and concerns about safety.
"It is more of a challenge to engage girls than boys. More girls seem not to enjoy activity, but a core group of boys define themselves as 'not sporty' if they are not good at football."
A project in South Lanarkshire involving groups such as the national dance agency YDance (Scottish Youth Dance) is proving that it is possible to get pupils on the move.
At Ballerup High in Greenhills, East Kilbride, teenage girls who were averse to PE are enthusiastic about a YDance contemporary street dance course.
Ashley Westran, 13, who has never been to dancing lessons before, says:
"It's been fun. I want to start dancing classes every week."
Her schoolmate Toni Gray, 13, adds: "I go to tap and modern dancing every Friday, so this has been easy. It's like the routines you see on pop videos and much better than PE."
Many children at the school, situated in a deprived area, have low self-esteem, but teachers believe their confidence has been significantly boosted, an idea evident in the performance they gave at the end of the course.
Carolyn Lappin, general manager of YDance, says similar schemes in local authorities across Scotland have been a big hit.
"We tailor projects to what a school or local authority wants to target," she says. "This East Kilbride programme was aimed at girls in sport to spur them into physical activities.
"The motivation is that they are doing something that they see on television every day. It's the pop video thing - they find it is something they can learn and improve in, and it really boosts their self-image."
Next year YDance plans to provide CD-Roms to every secondary school, with ideas about choreography and games that will encourage PE teachers to use dance steps in their lessons.
At the end of South Lanarkshire's first year in a three-year programme - operated over the secondary school sector and funded by the Big Lottery - the local authority says 6,000 children have benefited from taking part in these new activities.
Six programmes were established. The first, Girls in Sport, provides activities for 13 to 16-year-olds that they wouldn't normally get during the school day, such as dance, yoga and pilates, in conjunction with PE departments.
Gym Crowd gives every youngster in S2 and S3 in the local authority the chance to become a casual member of a local gym facility, and provides transport home afterwards.
A martial arts programme gives pupils in S1 to S4 the chance to attend after-school sessions with a coach.
No Limits offers after-school and weekend sports coaching for disabled youngsters; Rookie gives disadvantaged children the chance to train as lifeguards, with the added chance to work within the council's facilities afterwards; and Saturday morning sports clubs give youngsters access to 10 high school sports facilities and coaches.
Scott Dunbar, the Get Active co-ordinator at South Lanarkshire leisure department, says: "These are unique programmes that we devised. We identified kids and made sure that they had opportunities available to them, and the varied activities programmes have taken away a lot of barriers."